This project aims to enhance our understanding of the substantial degree of behavioral and neurobiological heterogeneity observed among disabled readers by characterizing the neurocognitive development of struggling readers whose reading is or is not at odds with their general cognitive abilities. This research will employ a hybrid cross-sectional/longitudinal design, recruiting two cohorts of children whose general cognitive and reading skills are both below average (operationally defined using achievement-based criteria;RD-A group): a younger cohort (mean age 7.5 years) and an older cohort (mean age 9.5 years). Both will be assessed with cognitive-behavioral and functional neuroimaging (fMRI) measures that target language and non-language cognitive skills;both cohorts will also be assessed behaviorally 12 months later. Comparison groups will be drawn from a recently funded grant (R01 HD48830;K. R. Pugh, PI) on which Dr. Landi is a collaborator. In that grant, the neurocognitive development of RD children whose reading skills are suppressed relative to their general cognitive abilities (operationally defined by traditional IQ-discrepancy criterion;RD-D group) and Typically Developing (TD) children will be tracked longitudinally for two years, from 7.5 to 9.5 years of age, using behavioral and functional neuroimaging (fMRI) measures (as well as MR spectroscopy and molecular-genetic measures). By partnering with the existing R01, the proposed project will directly study the continuum of language-specific versus general cognitive impairments in RD, collecting data for one cohort (the RD-A group), and yet making key comparisons to these other two cohorts (RD-D and TD). Specifically, this research aims to: (1) achieve a better understanding of early neurobiological and cognitive similarities/differences between RD children whose reading is (RD-D) or is not (RD-A) at odds with their general cognitive abilities, and Typically-Developing (TD) cohorts;(2) assess, longitudinally, the ways in which early neurobiological and cognitive profiles are predictive of subsequent reading development;and (3) examine, cross-sectionally, the neurobiological and cognitive development of RD-A readers over the 2-year period during which TD readers shift from beginning to fluent readers. Importantly, this research will provide much needed information about a subset of RD individuals (those who also present with general cognitive deficits) who have been relatively underrepresented in cognitive and educational research to date. This research may detect subtle etiological and neurobiological differences among RD children;ultimately such findings could improve our ability to individualize instructional approaches, optimizing treatment for the heterogeneous group of children who experience reading difficulties. This project is relevant to NIH's public health mission because it contributes to the understanding of the etiology and underlying neurobiology associated with reading disability (RD). Further it will provide an understanding of the relevant differences between two subtypes of reading disability;RD-Discrepant (reading is at odds with general cognitive abilities) and RD-Achievement (reading is commensurate with general cognitive ability), which will be useful for informing future treatment and remediation strategies for RD.